1. Field of the Invention
The present invention relates to window shades, and actuating systems used in window shades.
2. Description of the Related Art
Many types of window shades are currently available on the market, such as Venetian blinds, roller shades and honeycomb shades. The shade when lowered can cover the area of the window frame, which can reduce the amount of light entering the room through the window and provide increased privacy. Conventionally, the window shade is provided with an operating cord that can be actuated to raise or lower the window shade. More specifically, a drum may be operably rotated to wind and unwind a suspension cord to respectively raise and lower the shade.
However, the operating cord used in certain traditional window shade may have an excessive length, which affects the outer appearance of the window shade. Moreover, there is a risk of child strangle on the longer operating cord. To avoid the risk of accidental injuries, some window shades have no operating cord, and an operator can directly adjust the expansion of the window shade by vertically displacing a bottom rail of the window shade. This approach generally uses torsion springs to sustain the weight of the bottom rail, which requires the manufacturer to have a stock of different spring lengths for accommodating different sizes of window shades. The need to have different spring parts may increase the manufacture cost.
Therefore, there is a need for a window shade that is simple to operate, and address or improve at least the foregoing issues.